1. Field of the Invention
The present invention relates to a motor control circuit, a fan motor, electronic device, and a notebook personal computer.
2. Description of the Related Art
In a case where electronic device has a heating body that generates heat when operating the electronic device, the electronic device is usually provided with a fan motor for cooling the heating body. For example, in a case of a PC, server, etc., the operating frequency of a CPU has been getting higher year after year, which causes an increase in amount of heat generated from the CPU. For this reason, a PC (Personal Computer), server, etc., includes a fan motor for cooling a device to be cooled such as the CPU, a Hall element outputting a rotational position detection signal indicating a result of detection of a rotational position of the fan motor, and a motor control circuit rotating the fan motor in a predetermined direction based on a predetermined rotation control signal (see, e.g., Japanese Patent Application Laid-Open Publication Nos. 2003-204692, 2005-224100, and 2006-174648).
The Hall element is applied with a source voltage from a power supply dedicated to the Hall element or a power supply included in the motor control circuit, to operate, regardless of whether the rotation control signal for controlling the rotation of the motor is generated or not. That is, power consumption by the Hall element occurs even in a motor stop period during which the motor is not rotated by the motor control circuit, which causes lower efficiency in use of the Hall element source voltage, and may result in greater power consumption by the whole system.